A virus is a type of microbe that can exist in any conceivable place in the environment. It is a single-celled microorganism that needs another cell of a living organism to replicate. 

Usually, it enters the body through the mouth, nose, eyes, skin, genitals, or exposed wounds. Then, it invades a healthy cell in your body and multiplies itself. That is how diseases caused by viruses develop in the human body.Read ahead to understand the various types of viruses and the diseases they cause to protect yourself better.

Any disease resulting from a viral infection is called viral disease. Not all viral diseases are transmissible, which means they do not spread from direct contact. But many of those are highly contagious such as flu, cold, HIV, etc.

Different parts of the body, such as the respiratory and digestive systems, skin, nervous system, etc., can be affected by viral infections. They may present with symptoms like fever, fatigue, and muscle pain, but these particular signs can vary depending on the virus. The way these diseases spread and appear is essential for effective prevention and treatment.

Viruses spread through the body due to a variety of reasons and factors. Understanding how these infections spread is very important to prevent them.

• Direct body fluid contact with an infected person is one of the ways viral infections are transferred.
• Droplets emanating from coughs or sneezes transmit this type of virus.
• A virus can get on a surface and be picked up when someone touches their face after touching the contaminated surface.
• Mosquitoes are vectors that may transmit some viruses, such as those causing dengue fever and Zika virus.
• There are sexually transmitted viruses like HIV and human papillomavirus (HPV).
• Viruses such as hepatitis A and rotavirus can be spread through the consumption of food and drinks that have been contaminated.
• Hepatitis B, C, and other blood-borne viruses result from sharing needles or syringes with infected persons.

Here’s a brief overview of some frequently encountered viral illnesses. Below are some common viral diseases and their symptoms.

1. Gastrointestinal Diseases

These types of viral diseases affect your digestive system, causing gastroenteritis. In addition, stomach flues are highly contagious, spread through contaminated water and food.

Common Symptoms

• Stomach ache
• Vomiting
• Diarrhoea
• Nausea and headache
• Muscle ache
• Loss of appetite
• Dehydration

Examples

Names of some diseases caused by viruses in your digestive system are as follows:

• Rotavirus
• Adenovirus
• Astroviral infection
• Norovirus

2. Respiratory Diseases

Respiratory diseases are some of the most common diseases caused by viruses. These are highly contagious and spread through the sneeze droplet in the air. It starts affecting the upper respiratory tract and can escalate to the lower respiratory tract.

Common Symptoms

• Cough and sneeze
• Runny or stuffy nose
• Mild to high fever
• Body and muscle pain

Examples

Below are some names of viral respiratory diseases:

• Common cold
• Flu or influenza
• Infection from Parainfluenza virus
• Adenovirus infection
• SARS or Severe Acute Respiratory Syndrome
• Infection from Human Respiratory Syncytial virus

3. Hepatic Diseases

Hepatitis A, B and C viruses affect the human liver and cause inflammation. The disease can worsen if a patient continues with a poor diet and alcohol intake.

Common Symptoms

• Fever and fatigue
• Stomach ache
• Loss of appetite
• Pale stool
• Abdominal cramps
• Vomiting and jaundice

Examples

Hepatitis A, B, C, D and E are some hepatic diseases caused by the virus in humans.

4. Hemorrhagic Diseases

These viral diseases are acute conditions caused by a damaged cardiovascular system. Hemorrhagic illnesses or fevers can be life-threatening and attack many other organs of your body.

Common Symptoms

• Bleeding from mouth and ear
• High fever and fatigue
• Bleeding in the internal organs
• Body pain and headache
• Bleeding underneath the skin

Examples

Below are some examples of viral hemorrhagic illness:

• Dengue
• Yellow fever
• Lassa fever
• Ebola
• Marburg fever
• Crimean-Congo fever

5. Cutaneous Diseases

Cutaneous diseases constitute another type of diseases caused by viruses that affect the integumentary system or epidermis. It causes skin lesions that may be persisting for a long while.

Common Symptoms

• Flat or raised red spot
• Rough and scaly skin
• Lesions or sores
• Painful or itchy rash
• Skin patches

Examples

The followings are some examples of cutaneous diseases -

• Molluscum contagiosum or water warts
• Genital warts and oral warts
• Painful and itchy genital
• Chickenpox
• Measles

6. Neurologic Diseases

These diseases take place once the virus attacks your central nervous system. It can cause severe damage to your brain and spinal cord. Most of these viral infections are asymptomatic but can have life-threatening consequences.

Common Symptoms

• Fever
• Confusion
• Dizziness
• Memory loss
• Problem to coordinate

Examples

Below are some neurological diseases caused by viruses:

• Acute Flaccid Paralysis or Polio
• Viral Encephalitis
• Meningitis
• Rabies

Primarily, these viral diseases are sexually transmitted infections that can influence the genital, genitourinary, and reproductive systems. In the respective areas, they often lead to localised manifestations and may also compromise sexual well-being in general.
Common Symptoms

• Genital sores or warts
• Discharge from the genital area
• Pain during intercourse
• Itching or irritation

Examples

• Human Immunodeficiency Virus (HIV)
• Herpes Simplex Virus (HSV)
• Human Papillomavirus (HPV)
• Hepatitis B

These viral infections affect numerous body systems, resulting in generalized symptoms and possible complications. Systemic reactions like fever and rash can occur as the infections impact different organs and systems.

Common Symptoms

• Fever
• Rash
• Joint pain

Examples

• Fatigue
• Measles
• Chickenpox
• Smallpox
• COVID-19

Encephalitides are grave viral infections that prompt brain inflammation, causing various signs, from mild influenza-like symptoms to severe neurological impairments. These diseases can severely influence cognitive and nervous function.

Common Symptoms

• Severe headache
• Seizures
• Altered mental status
• Sensitivity to light

Examples

• West Nile Virus
• Japanese Encephalitis
• Tick-Borne Encephalitis

These are frequently severe types of infection that rarely occur among healthy people but in individuals with compromised immune function due to underlying conditions. They commonly manifest as severe atypical infections necessitating specialized therapeutic strategies.

Common Symptoms

• Persistent infections
• Unexplained weight loss
• Frequent or severe illness

Examples

• Cytomegalovirus (CMV) infection
• Kaposi's Sarcoma (associated with HIV/AIDS)
• Pneumocystis Pneumonia (PCP) 

The overall impact of viral damage can range from mild, temporary symptoms to severe, life-threatening conditions, depending on the virus and the individual's health. Viral infections can damage various parts of the body in humans.

• Viruses may destroy cells by taking over cellular machinery, causing their death and tissue damage.
• This may lead to diseases such as pneumonia, hepatitis, or encephalitis, depending on the affected organ.
• Long-term health complications, including liver cirrhosis, immune system suppression, and even cancer, could result from chronic viral infections such as HIV or hepatitis B.

Significant damage can also occur through the body's immune response to viral infection.

• Inflammation caused by the virus-infected body can cause cases such as myocarditis (inflammation of heart muscle) and meningitis (swelling around the brain and spinal cord).
• Some viruses have the potential to cause genetic mutations, while others initiate autoimmune responses whereby the body incorrectly attacks its tissues.

The extent to which viral damages are harmful depends on an individual's health conditions and the type of pathogen involved, ranging from temporary light symptoms to intense life-threatening conditions.

Several factors enhance the likelihood of contracting viral diseases or experiencing severe consequences, such as:

• Infection risk is increased by a weakened immune system.
• The very young and the old are at a higher risk.
• Viral infections can be worsened by chronic conditions.
• Close contact with people who have been infected increases the spread of viruses.
• Viruses spread easily where there is poor hygiene in place.
• Visiting outbreak areas is a risk factor for infection.
• Sexual transmission of viruses is enhanced through unprotected sex.
• Preventable viral infections become more likely because of a lack of vaccination.
• Riskier professions like healthcare increase the chances of infection.
• Risk can also be increased by environmental factors such as insects, pollutants, etc.

Treatment for viral illnesses includes symptom management and supportive therapy. Among them are antiviral medications, vaccines, and supportive care to help the body fight off the virus effectively.

• Antiviral Medications: They prevent viruses from spreading and cause less severe infections by blocking viral replication within host cells. These medicines also help lower viral loads and relieve related symptoms.
• Vaccines: They stimulate the immune system to develop immunity against specific viruses, preventing future infections. They are important because they are fundamental in long-term disease prevention and management.
• Rest and Hydration: They are important because they support the body's natural healing processes during sickness through adequate rest and fluid intake. This allows the immune system to work more efficiently.
• Supportive Care: In addition to managing complications that arise, nutritional support must be offered for it to be considered complete. It helps patients regain health and maintain it at optimum levels.
• Isolation: Separation of patients who others have infected to reduce virus spread and community transmission. The most effective way of controlling an outbreak is through isolation measures.
• Hospitalisation: Medical attention, which includes treatment plans, needs to be given to such cases that require 24/7 care and monitoring, among others; hence, it ensures appropriate and timely interventions for them.

Prevention from viral infections is not entirely possible as they dwell everywhere. However, maintaining proper hygiene and not sharing your belongings mitigate the risk significantly. Additionally, you must cover your face and wounds to protect yourself from the spread of a virus.

Apart from these safety measures, you must eat healthy and consume fresh food daily. It will strengthen your immune system and fight and cure the diseases caused by viruses.

If you have flu or any other viral infection, the health insurance company can possibly cater for visits to the doctor and lab tests that involve prescribing antiviral drugs. The level of coverage might also differ, as well as the particular viral infection, depending on your insurance plan.

Some plans may need pre-authorisation or not allow certain treatments at all. Just read your policy details because it will help you know about out-of-pocket expense coverage, apart from ensuring you get better copayments and deductibles.

Viruses are responsible for different illnesses, varying in strength from mild to severe. It is important to understand different types of viral infections, signs pointing towards their occurrence, risk factors involved, and possible treatment options for effective management and prevention. One must be knowledgeable enough regarding these diseases so that they do not occur, and one must also know when to consult a doctor.